Sidewall blank for substantially eliminating twist in deep bottom containers

ABSTRACT

A cup forming sidewall blank includes a piece of flexible sheet material having an upper edge, a lower edge, and a pair of opposite side edges with an area at or adjacent the lower edge of the sidewall blank being provided with relief formations which extend generally upwardly and perpendicularly relative to the lower edge. The relief formations preferably take the form of score lines, slits, notches or other suitable constructions which are generally spaced from one another and are of equal length relative to the sidewall blank lower edge.

CROSS REFERENCE TO RELATED APPLICATION

The present application relates to and claims priority of U.S.Provisional Patent Application Ser. No. 61/376,001, filed Aug. 23, 2010.

FIELD OF THE INVENTION

The present disclosure relates to the manufacture of two piece, seamedpaper cups coated with thermoplastic, and more particularly, pertains tothe manufacture of cups having a deep bottom formation.

BACKGROUND OF THE INVENTION

The assignee of the instant application, Paper Machinery Corporation ofMilwaukee, Wis., USA, is the manufacturer of paper cup making machinesused to make to a variety of cups and containers. A typical cup machinefor making paper cups, for instance, includes a turret having aplurality of mandrels about which the containers are formed. The turretsequentially rotates the mandrels into cooperation with a variety ofworkstations where numerous cup forming procedures occur.

In an exemplary procedure, a circular bottom blank is cutout at oneworkstation and attached to the end of a mandrel by a vacuum appliedthrough the mandrel. During this procedure, the outside edge or lip ofthe bottom blank is folded downwardly. At a subsequent workstation, asidewall blank is wrapped around the mandrel. The sidewall blank isheated and sealed along an overlapped side seam which runs generallylongitudinally along the side of the cup. Typically, a paperboard iscoated with a thermoplastic material such as polyethylene, polypropyleneor a solid plastic sheet can be used, so the bottom and sidewall blanksmay be heated and sealed together. In some applications, the sidewallblank includes a flap extending beyond the lip of the bottom blank, andthis flap is bent over the lip. At a bottom finishing station, the flapis pressed against the lip from an inside recessed area of the bottom ofthe cup. By heating the thermoplastic and firmly pressing the sidewall,sidewall flap and bottom flap lid together, a bottom seal is formed andthe cup is provided with a sturdy bottom region having a recessed area.There may be also workstations where various other additional cupforming procedures are carried out. For example, one station may be usedto provide a curl at the top or rim of the cup to provide a morefunctional drinking container and a better appearance.

Certain cups are manufactured according to the above exemplary procedurewith a deep bottom formation in which the recessed area is defined by abottom which is raised and spaced typically about ½″-⅝″ from thelowermost peripheral edge that supports the cup. Traditionally, theexternal peripheral surface of the deep bottom formation on the cupresults in an undesirable twist or wrinkle effect (as depicted at T inthe cup C of FIG. 1) which detracts from the appearance of the cup andcan result in potential leakage problems.

Accordingly, it is desirable to substantially eliminate the twist orwrinkle effect that normally occurs in the formation of deep bottom cupsand containers to provide a smooth, uniform aesthetic appearance on theexternal surface of the lowermost or bottom region and prevent leakagetherefrom.

SUMMARY OF THE INVENTION

The present disclosure relates to a two piece cup formed by a sidewallblank having an upper edge, a lower edge, a pair of opposite side edges,a front surface and a back surface with the opposite side edgesoverlapped and sealed along an overlapped side seam to a bottom blankalong a lower edge of the sidewall blank. The invention is improvedwherein an area at or adjacent the lower edge of the sidewall blank isprovided with relief formations which extend generally upwardly andperpendicularly relative to the lower edge. The relief formationspreferably take the form of score lines, slits, notches or othersuitable constructions which are generally equally spaced from oneanother and are of equal length relative to the sidewall blank loweredge.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings:

FIG. 1 is a front view of a prior art formed two piece cup exhibiting atwist on the external surface of the lowermost region of the cup;

FIG. 2 is a perspective view of a formed two piece cup constructed usingthe sidewall blank of the present invention;

FIG. 3 is a schematic plan view of an exemplary cup making machine formaking a cup with the sidewall blank of the present invention;

FIG. 4 is a perspective representation of a bottom blank and a sidewallblank used in forming a cup shown in FIG. 2;

FIG. 5 is a sectional view showing the area at which the sidewall blankis joined to the bottom blanks;

FIG. 6 is a plan view of the sidewall blank of FIG. 4 illustrating oneembodiment of the present invention;

FIG. 7 is a plan view of a second embodiment of the sidewall blank usedto form the cup of FIG. 2; and

FIG. 8 is a plan view of a third embodiment of the sidewall blank usedto form the cup of FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring generally to FIG. 3, an exemplary cup making machine 20 isillustrated. This particular design includes a mandrel turret 22 whichcooperates with a transfer turret 24 and a rimming turret 26. Mandrelturret 22 includes a plurality of mandrels 28 that are rotated in astepwise or indexing manner between a surrounding workstations. Forexample, a bottom blank may be applied to a given mandrel 28 at a bottomblank maker workstation 30 and then rotated to a bottom reformer station32. From this point, the mandrel 28 is rotated into cooperation with thetransfer turret 24 which receives sidewall blanks from a hopper 34 androtates the sidewall blank into cooperation with an adjacent mandrel 28.The sidewall blank is then folded about the mandrel over the bottomblank, heated and sealed along a side seam where the opposite side edgesof the sidewall blank overlap.

Next, the bottom blank and the sidewall blank are rotated to a bottomheat station 36. After heating, mandrel turret 22 indexes the subjectmandrel 28 into registration with a roller incurl workstation 38 where aportion of the sidewall blank, i.e. a sidewall blank flap, is bent overan outer lip of the bottom blank to form a recessed bottom in the cup.The cup is then moved to a bottom finishing station 40 where thesidewall blank flap and the bottom blank lip are pressed against thelower region of the sidewall blank to form a bottom seal.

Once the bottom is formed and sealed, the seal is transferred to rimmingturret 26, rotated to a lube station 42 and then rotated to a rimmingprecurl station 44 where the upper lip of the sidewall is curledoutwardly. From that station, the cup is indexed to a rimming finishcurl station 46 which finishes the curled portion along the top of thecup to make an attractive edge. At this point, the cup may be moved toan optional lid groover station 48 and then to a cup blow off station 54for removal of the finished cup.

Referring to FIGS. 2, 4 and 5, an exemplary cup 52 includes an upperregion 54 having a curled rim 56 and a bottom region 58. Cup 52 is madefrom a flexible sheet member or sidewall blank 60 of generallytrapezoidal shape which is wrapped around a circular bottom blank 62disposed generally transverse thereto. Sidewall blank 60 has front andback surfaces as well as opposite side edges 60 a, 60 b, an upper curvededge 60 c and a lower curved edge 60 d. Bottom blank 62 is typicallybent or folded over in proximity to its outer edge to form a lip 64. Thesidewall blank 60 is located with respect to bottom blank 62 so that aflap portion 66 having a bottom edge 65 extends beyond lip 64. Flapportion 66 is bent or folded around lip 65 so lip 64 may be squeezedbetween flap portions 66 and the lower region of sidewall blank 60.

A typical cup 52 is made from paperboard blanks having a thermoplasticcoating such as polyethylene. The thermoplastic material permits heatingand sealing of adjacent components. For example, when sidewall blank 60is wrapped around bottom blank 62, adjacent overlapped edges 60 a, 60 bare heated and pressed together along an overlapped side seam 68.Similarly, lip 64, flap portion 66 and lower region 67 of sidewall blank60 may be heated and pressed together at a bottom finish station 40 toform a strong, leak-proof bottom region 58. By forming cup 52 asillustrated in FIG. 5, a recessed area 70 is created in the bottom ofcup 52 on an opposite side of bottom blank 62 from the main containerregion of cup 52. Recessed area 70 permits insertion of a tool to presslip 64 and flap portion 66 to the lower region 67 of sidewall blank 60and form the bottom seal.

In accordance with the present invention, the sidewall blank 60 isprovided with relief formations at selected locations relative to thelower edge so as to overcome the twist or wrinkle effect discussed inthe Background of the Invention, and improve the quality of the bottomregion of the cup 52.

Referring now to FIGS. 4 and 6, the sidewall blank 60 is formed on frontand back surfaces with a series of score lines 72 that extend upwardlyand perpendicularly from the lower edge 60 d. Preferably, the scorelines 72 are equally spaced from one another and are of equal length.

FIG. 7 shows another embodiment of sidewall blank 60 wherein a series ofslits 74 are formed therethrough adjacent the lower edge 60 d. Again,the slits 74 extend upwardly and perpendicularly relative to the loweredge 60 d, are preferably equally spaced from one another and are ofequal length.

FIG. 8 shows a further embodiment of the sidewall blank 60 wherein aseries of inverted V-shaped notches 76 is formed along the lower edge 60d. The notches 76 extend upwardly from the lower edge 60 d, arepreferably of equal size and preferably are equally spaced from oneanother.

The score lines 72, slits 74 and notches 76 collectively define reliefformations at or adjacent the lower edge 60 d of each sidewall blank 60.Such relief formations generally extend continuously across the lengthof the lower edge 60 d. When deep bottom cups such as 52, FIG. 2 areformed using the sidewall blanks 60 with the relief formations formedalong the lower edges 60 d as described above, the undesirable twist orwrinkle effect is eliminated, and a smooth aesthetically pleasingexternal peripheral surface is formed in the lowermost region of thecup. The manufacture of such deep bottom cups using the sidewall blank60 with such relief formations 72, 74, 76 has also been found to bebeneficial in preventing leaks in the bottom of the cups.

While the invention has been described with reference to a preferredembodiment, those skilled in the art will appreciate the certainsubstitutions, alternations, and omissions may be made without departingfrom the spirit thereof. Accordingly, the foregoing description is meantto be exemplary only and should not be deemed limitative on the scope ofthe invention set forth with the following claims.

What is claimed is:
 1. In a two piece cup formed by a sidewall memberhaving an upper edge, a lower edge and pair of opposite side edgesoverlapped and sealed along an overlapped side seam. and a bottom membersealed along the lower edge of the sidewall member, the improvementcomprising: a plurality of relief formations provided at or adjacent thelower edge of the sidewall member.
 2. The improvement of claim 1,wherein the relief formations extend upwardly from the lower edge. 3.The improvement of claim 1, wherein the relief formations extendperpendicularly from the lower edge.
 4. The improvement of claim 1,wherein the relief formations are equally spaced from one another. 5.The improvement of claim 1, wherein the relief formations extendcontinuously along a length of the lower edge.
 6. The improvement ofclaim 1, wherein the relief formations are formed as a series of scorelines.
 7. The improvement of claim 1, wherein the relief formations areformed as a series of slits.
 8. The improvement of claim 1, wherein therelief formations are formed as a series of inverted V-shaped notches.9. The improvement of claim 1, wherein the relief formations are ofequal size.
 10. A two piece cup comprising: a sidewall member having anupper edge, a lower edge, a pair of opposite side edges overlapped andsealed together along an overlapping side seam; and a bottom membersealed along the lower edge of the sidewall member, wherein a pluralityof relief formations are formed at or adjacent the lower edge of thesidewall member such that undesirable wrinkle effects normally incurredduring bottom formation of the cup which lead to leaking problems areprevented.
 11. A cup forming sidewall blank comprising: a piece offlexible sheet material having an upper edge, a lower edge and pair ofopposite side edges wherein the lower edge is provided with a series ofspaced apart relief formations extending upwardly therefrom.
 12. Thesidewall blank of claim 11, wherein the sheet material has a generallytrapezoidal shape.